Carbon fiber or glass fiber resin is a composite material being made with carbon fiber or glass fiber as reinforcing phase mingled in a resin as matrix phase. It meets the requirements to wire core material of the novel power transmission line in power industry, because of a series of outstanding performance thereof, such as, high specific strength, high specific modulus, high temperature resistance, corrosion resistance, fatigue resistance, and creep resistance, as well as small sag and thermal expansion coefficient, thereby gradually emerging a new configuration of carbon fiber composite core with the center layer of carbon fiber or resin and the coating layer of glass fiber or resin, as time required. It is found that, in subsequent studies, compared with conventional a steel core, the quality and linear expansion coefficient of the carbon fiber or glass fiber composite core equals approximately to ⅕ and 1/12 thereof, respectively. The outer layer, namely coating layer of glass fiber reinforces the wear resistance of the wire rod-type specimens, and is conducive to alleviate the damage generated between the wire rod-type specimens and an aluminum wire. The smooth surface of the wire rod-type specimens enables mating it directly with soft aluminum wire with trapezoidal cross section without processing, that is available for possibility and necessity of its application in transmission overhead line industry, further decrease of the power consumption during transmission, and reduction of 20% quantities of tower rods for land saving, as well as reduction of the metal resource consumption, thus contributing to the implementation of a power grid with environmental protection and power saving of high efficiency.
In order to facilitating the transport and discharge of transmission wire, generally winding its core composite around a disk of reasonable size. For more delivery quantities of wire, it is usually chosen that winding the core composite around the disk in a size as small as possible. However, carbon fiber or glass fiber composite core is configured with high elastic modulus and low elongation that the outer layer of its glass fiber being exposed is prone to cause the exposed surface defects where scratches or damages is not to be promptly detected, the use of the undersized disk may in turn lead to make the wire rod-type specimens damaged or even broken.
There is a need, therefore, for how to quickly and effectively estimate the exposed surface defects of the carbon fiber or glass fiber composite core, and to provide a safe and reasonable radius of curvature for the transport and discharge of the carbon fiber or glass fiber composite core line. A need exists for the primary issue as aforementioned that promotes safe operation of transmission line in new power industry.